Effect of atmospheric humidity and nitrogen level on the formation and water use efficiency of winter wheat

Winter wheat (“Zhengmai No. 9023”) was treated with two levels of atmospheric humidity (85% RH and 35% RH) and three levels of nitrogen (0, 150 mg·kg^-1 and 300 mg·kg^-1) in large artificial intelligent chambers. The responses of wheat height, tiller number, leaf area, dry matter accumulation and water use efficiency to different treatments were analyzed. The study showed that while high air humidity increased height and leaf area, but it decreased tiller number of winter wheat under zero to medium nitrogen treatments. The effect of humidity on wheat dry matter accumulation depended on nitrogen application level. High humidity significantly improved wheat biomass accumulation and reduced root/shoot ratio under medium nitrogen treatment. High humidity also reduced water consumption, whereas medium to high nitrogen treatments enhanced water use efficiency in winter wheat. Furthermore, water use efficiency under medium and high nitrogen treatments was significantly higher than under zero nitrogen treatment.